1. Field of the Invention
The present invention relates to a liquid crystal display.
2. Discussion of the Background
A liquid crystal display (LCD) is one of the most widely used flat panel displays (FPD), and is composed of two display panels on which electrodes are formed, and a liquid crystal layer interposed between the two display panels. A voltage is applied to the electrodes to generate an electric field on the liquid crystal layer, and the orientation of liquid crystal molecules in the liquid crystal layer is determined and the polarization of incident light is controlled through the generated electric field to display an image.
A widely used LCD has a structure in which field generating electrodes are respectively formed on two display panels. Among the two display panels, a plurality of pixel electrodes and thin film transistors are arranged in a matrix format on one display panel (hereafter referred to as a “thin film array panel”), color filters of red, green, and blue and a light blocking member are formed on the other display panel (hereafter referred to as a “common electrode panel”), and one common electrode covers the entire surface of the other display panel.
However, when the pixel electrodes and the color filters are formed on different display panels, it may be difficult to correctly align the pixel electrodes and the color filters, which may cause an alignment error. To solve this problem, a color filter on array (COA) structure may be used in which the pixel electrodes and the color filters may be formed on the same display panel.
Also, when considering a combination margin of the thin film transistor array panel and the common electrode panel, a light blocking member such as a black matrix may be formed with a larger than predetermined size. However, the aperture ratio may be decreased by the size of the black matrix so that the black matrix may alternatively be formed in the thin film transistor array panel.
An interval of the liquid crystal layer between two display panels is referred to as a cell gap, and the cell gap influences general operation characteristics of the LCD such as response speed, contrast ratio, viewing angle, and luminance uniformity. If the cell gap is not uniform, a uniform image may not be displayed on the whole screen, which may deteriorate the display quality. Accordingly, a plurality of spacers may be formed on one of the two panels to maintain the uniform cell gap throughout the whole region of the substrate.
The light blocking member including the black matrix prevents light leakage at the boundary of the pixels and a non-display area at the circumference of the display area. The spacer and the light blocking member may be simultaneously formed to simplify a manufacturing process. However, when the height of the spacer is low, it may be difficult to form the light blocking member with sufficient optical density to prevent light leakage in the non-display area.